The reference to any prior art in this specification is not, and should not be taken as an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge.
Open pit mining is a common method for extracting valuable material such as coal.
Turning to FIG. 1, a typical open pit coal mining system 100 includes blasted waste overburden 102 upon which a dragline 104 is located. The dragline 104 lifts and removes the overburden 102 forming a moving strip mine highwall 106 of an open pit 108 to expose a coal seam 110 in the mine pit 108. The dragline 104 piles the overburden 102 in parallel rows, colloquially termed low wall spoil 112, as the dragline 104 moves along forming the pit 108. This sequence is typical of an overall mining system termed a strip mine. However, embodiments of the present invention equally apply to a non-strip mining systems.
An excavator (or front end loader or face shovel) 114 is located at the floor 116 of the pit 108. The excavator 114 excavates the coal 110 and loads it into pit haulage trucks 118 on the pit floor 116. The low speed trucks 118 are specialized off road vehicles specifically designed to cater for the often undulating and uneven nature of the pit floor 116 whilst accessing the excavator 114 loading area, and which also have high power engines and driveline systems which are capable of transporting the material up and out of the pit 108. The trucks 118 gain access to the pit 108 via specially constructed haulage access ramps 120 which are formed through the low wall spoil 112. The ramps 120 are specifically developed at a gradient that optimally permits the trucks to traverse up the ramp 120 with a full load of material, as well as returning empty down the ramp safely and specifically within the design limits of the trucks' braking systems. The ramps 120 are periodically created along the strip mine pit 108, which not only involves the removal and/or relocation of significant amounts of overburden waste material to form the ramps 120, but also involves the need to find a location to deposit that material away from the ramp area.
Upon loading, the trucks 118 exit the pit 108 via the ramps 120, making the often long and arduous journey up the ramps 120 to the top of the mine pit 108, and thence they transport the valuable material to the mineral processing plant which is typically located some distance away from the open pit.
FIGS. 1A and 1C clearly show the ramps 120 with a 60 meter wide strip mine pit 108. The overall dimensions of the exampled worked mining system 100 are 3,000 meter length and 1,200 meter width. As can best be seen in FIG. 1B, the low wall spoil 112 includes a pre-strip volume 122 piled high upon a dragline volume 124. After mining ceases, the low wall spoil 112 is levelled out to fill in the ramps 120 and rehabilitate the land.
In recent times, the value of coal and other minerals has dipped. The adverse economic burden placed on miners has resulted in the closure of existing mines and a deferment on the creation of new mines.
Embodiments of the present invention provide increased efficiencies and lower energy consumption, resulting in improved mining techniques and reduced costs in order to sustain mining profitability in view of falling mineral prices.